Tuesday, 17 September 2024
Spectacular reconstructions of the neurons of the human cortex
The problem with scientific research is that it never stops. Recently, my friend Jean-Pierre, who keeps a close eye on new articles in major neuroscientific journals, let me know about a major paper just published in Science, about how electron microscopy is now being used to reconstruct neurons of the human cortex with unequalled precision. And since this research had been done by Jeff Lichtman’s team at Harvard, and I had already written a post about it in this blog back in 2014 , I figured that I had better write another post about it now, because the images of neurons that this team has succeeded in producing recently are truly spectacular. For example, the image above represents one neuron with 5600 axons (blue) making synaptic connections (green)). (more…)
From the Simple to the Complex | Comments Closed
Monday, 19 August 2024
Discovery of the “jailer” in our neurons
Today I’d like to say a few words about a phenomenon that is related to neuronal plasticity and that I’d never heard of before. I learned about it in a book entitled Seeing the Mind: Spectacular Images from Neuroscience, and What They Reveal about Our Neuronal Selves, by French cognitive psychologist Stanislas Dehaene. Actually, I read the original French edition, published in 2021, but I don’t have access to the English edition, published in 2023, so the following excerpt is my own translation:
As we age, certain neurons, and especially the large inhibitory neurons that control the activity of their surroundings, become wrapped in a perineuronal net,a rigid lattice that holds them still. This aggregate of proteins and sugar chains, which has some of the same ingredients as cartilage, prevents the nerve cells from changing. Hence they cannot form new connections or even alter existing ones; emprisoned in this net, the neuron loses its plasticity.
From the Simple to the Complex | Comments Closed
Wednesday, 24 July 2024
How Andy Clark’s career path mirrors that of cognitive science over the past 40 years
This week I’m just going to copy and paste a paragraph from a chapter of my book ( to be released in French on October 1, 2024 ) in which I describe the career of Andy Clark, an important philosopher of cognitive science, and draw your particular attention to his latest book, The Experience Machine: How Our Minds Predict and Shape Reality, which he discusses in this stimulating interview.
I will start by just briefly describing the career of Andy Clark, a philosopher of cognitive science whom I like a lot, and his encounter with Karl Friston. Because Clark’s career path, all on its own, sums up the major trends in cognitive science over the past 40 years that I talked to you about at our first meeting. First, in keep with the cognitivist paradigm that prevailed at the time, he studied symbolic artificial intelligence, also known as computationalism. Then he became interested in connectionism— in virtual neural networks, thus more closely approximating the human brain, which can learn by modifying its internal connections. After that, he jumped aboard the train of embodied cognition, thus including the entire body in the equation of our cognitive processes, and even the objects in our environment (the concept of extended cognition, of which is he one of the most ardent proponents). And lastly, he made important contributions to the Karl Friston’s bold ideas about predictive processing, the principle of free energy and active inference—in short,all of the concepts whose broad implications I will now discuss.
From the Simple to the Complex, From Thought to Language | Comments Closed
Tuesday, 25 June 2024
Earworms as an excuse to talk about mental simulations and working memory
This week I’d like to talk about an intriguing phenomenon: earworms, those bits of songs that start playing in your head for hours and sometimes even days on end. More specifically, I’d like to talk about a comment that biologist John Medina makes about earworms in an entry entitled “As the Worm Turns” in his substack “John Medina’s Brain Rules”. I call it a comment because, as Medina admits right off, no one really knows much about what causes earworms. But the two neurological considerations that he raises are still interesting. They relate to two key concepts that I of course discuss on my website: mental simulation and working memory. (more…)
Memory and the Brain | Comments Closed
Tuesday, 30 April 2024
The so-called second brain in your intestines
After I deliver lectures about the human brain, one question that people often ask me is, “Is there really a ‘second brain’ in my belly, and if so, how is that possible?” I have to tell them that for someone like me, who many years ago did his master’s research on an invertebrate—more specifically, on a marine mollusk called the sea slug—there’s nothing surprising about finding neurons in parts of the body besides the brain. Because, like my sea slug, the phylogenetically oldest animals on Earth began by having clusters of neurons (what are often called ganglia) in many different parts of their bodies. For example, the sea slug has ganglia in its mouth, feet, and brain (where the ganglia are no bigger than anywhere else) as well as in its abdomen . It was only later in evolution, and especially in vertebrates, that increasing cephalization occurred: a concentration of neurons in the rostral portion of the neural tube (in other words, in the head). But that doesn’t mean that the other neurons, such as those in the abdomen, disappeared! (more…)
From the Simple to the Complex | Comments Closed
